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    <script>

        // 修改变量的值 ,需要重新赋值
        // = 赋值运算符 把等号右边的  赋值给  左边
        // var a =100;
        // a = 'hello';

        var a = 1;
        var b = 2;
        var c = 3;
        a = b + c; 
        b = c - a;
        c = a * b;
        console.log(a); //5
        console.log(b); //-2
        console.log(c); //-10

    </script>
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